Analysis of antibody reactivity against cysteine sulfinic acid decarboxylase, a pyridoxal phosphate-dependent enzyme, in endocrine autoimmune disease

• The structurally related group II pyridoxal phosphate (PLP)-dependent amino acid decarboxylases glutamic acid decarboxylase (GAD), aromatic L-amino acid decarboxylase (AADC), and histidine decarboxylase (HDC) are known autoantigens in endocrine disorders. We report, for the first time, the prevalence of serum autoantibody reactivity against cysteine sulfinic acid decarboxylase (CSAD), an enzyme that shares 50% amino acid identity with the 65- and 67-kDa isoforms of GAD (GAD-65 and GAD-67), in endocrine autoimmune disease. Three of 83 patients (3.6%) with autoimmune polyendocrine syndrome type 1 (APS1) were anti-CSAD positive in a radioimmunoprecipitation assay. Anti-CSAD antibodies cross-reacted with GAD-65, and the anti-CSAD-positive sera were also reactive with AADC and HDC. The low frequency of anti-CSAD reactivity is in striking contrast to the prevalence of antibodies against GAD-65, AADC, and HDC in APS1 patients, suggesting that different mechanisms control the immunological tolerance toward CSAD and the other group II decarboxylases. Moreover, CSAD may be a useful mold for the construction of recombinant chimerical antigens in attempts to map conformational epitopes on other group II PLP-dependent amino acid decarboxylases.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Annan klinisk medicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Other Clinical Medicine (hsv//eng)

Keyword

Addison Disease/immunology

Aromatic-L-Amino-Acid Decarboxylases/immunology

Autoantibodies/*blood/immunology

Carboxy-Lyases/*immunology

Cross Reactions

Diabetes Mellitus; Type 1/immunology

Female

Glutamate Decarboxylase/immunology

Histidine Decarboxylase/immunology

Humans

Isoenzymes/immunology

Male

Polyendocrinopathies; Autoimmune/*immunology

Pyridoxal Phosphate/metabolism

Radioimmunoprecipitation Assay

Research Support; Non-U.S. Gov't

MEDICINE

MEDICIN

Publication and Content Type

vet (subject category)

art (subject category)